Microdus is closely related to Dicranella, but it differs in having smaller, more delicate leaves and somewhat reduced peristome with teeth that are usually undivided, papillose, and rather irregularly striate from the base to the middle. Both genera have species with warty and papillose spores. Microdus has been treated as a synonym of Dicranella by several authors, such as Allen (1994). Species of Microdus are mainly distributed in tropical regions of the world with two distributional centers in tropical America and tropical Asia. Three species are currently recognized in China.

P.-J. Lin et al. (1992) reported Microdus miquelianus (Mont.) Besch. from Hainan Island [Jianfengling Mts., P.-C. Wu, Z.-H. Li & P.-J. Lin 85153 (IBSC, PE)], but we could not confirm the report. Microdus miquelianus is very similar to M. brasiliensis, but it differs in having more strongly thickened leaf cell walls, elongate-ovoid to narrowly cylindric capsules, and reddish setae. In contrast, Microdus brasiliensis has ovoid capsules and yellowish setae. The occurrence of this species in China needs further study.